The present invention relates to a package structure of a multi-hip module and more particularly to a package structure with a heat transfer structure of a multi-hip module having a plurality of highly heat-generating semiconductor devices with high speed performances for use in an electronic device such as note-type personal computers.
In recent years, there has been required scaling down and reduction in weight of electronic devices packaging high speed and high level function semiconductor devices, typically note type personal computers. Satisfactions to those requirements for scaling down and reduction in weight of electronic devices packaging high speed and high level function semiconductor devices raises a serious and practical problem with how to transfer or radiate generated heat to outside of the electronic devices. The packaging structure of the semiconductor devices is important for efficiently transferring and radiating the generated heat to outside of the electronic devices
In prior art, various types of semiconductor packaging structures had been proposed. FIG. 1 is a cross sectional elevation view illustrative of a conventional semiconductor packaging structure with a high heat transfer structure on which a heat sink 20 is provided. Another conventional semiconductor packaging structure has a micro-fun with a heat sink for compulsory air-cooling system. Still another conventional semiconductor packaging structure has a combination of a heat pipe and a micro-fun.
Yet another heat transfer structure is disclosed in Japanese laid-open patent publication No. 5-95060, wherein a circuit board is fixed with a fixed type spring metal part which is formed with a cleaved groove and a recessed portion. Heat radiation fins are slid into the grooves so that the heat radiation fin is held over the semiconductor device by a surface contact and a proper tension by a spring force.
Further another heat transfer structure is disclosed in Japanese laid-open patent publication No. 4-10558, wherein a quad flat package is tightly covered with and surrounded by a corrugate-shaped metal heat radiation plate so that the quad flat package is caulked by the corrugate-shaped metal heat radiation plate.
Furthermore another heat transfer structure is disclosed in Japanese laid-open patent publication No. 6-21277, wherein a heat radiation plate is provided in a gap between a semiconductor package of pin grid array or quad flat package and a printed wiring board for heat transfer from the semiconductor package through the heat radiation plate to the printed wring board.
If the heat sink or the micro-fun is provided over the semiconductor package under the requirement for reduction in height and scaling down of the electronic device such as note type personal computers, then the heat sink and the micro-fun are limited in height whereby the heat radiation effect is reduced. Such the heat radiation structure is not responsible to high power electronic devices such as advanced semiconductor devices with high speed performance. Further, an excess mechanical stress is applied onto the semiconductor device when the heat sink is provided on the semiconductor package. The other heat transfer structure using the heat pipe is engaged with another problem with increased cost of the electronic device.
The above conventional heat transfer structure disclosed in Japanese laid-open patent publication No. 5-95060 is engaged with the following problem. The heat generated from the semiconductor device is transferred from the radiation fins by air-convection current. It is difficult to transfer a large amount of heat generated. Further, the spring metal fitting is pressed onto the semiconductor device and the spring metal fitting is fixed to the printed board, for which reason although it is possible to prevent the application of the excess thermal stress onto the semiconductor device, it is difficult for the fixed type spring metal fittings to make uniform the pressing forces to metal bumps. This means that the excess thermal stress is likely to be applied to the semiconductor device or the printed board.
The above conventional heat transfer structure disclosed in Japanese laid-open patent publication No. 4-10558 is engaged with the following problem. It is difficult to adjust a pressing force between the heat radiator and the quad flat package. Cracking and braking are likely to be caused at stress singular point of the heat radiator and the quad flat package. Further, cracking is also likely to be caused at a cramped portion of the printed board.
The above conventional heat transfer structure disclosed in Japanese laid-open patent publication No. 6-21277 is engaged with the following problem. A heat radiation effect or a heat radiation efficiency is insufficient because the heat generated is transferred through the contact surface between the substrate and the heat conductive material.
In the above circumstances, it had been required to develop a novel heat transfer structure of a semiconductor package for multi-chip module.